Chemical tests

A few routine tests are usually performed on CSF samples.

CSF glucose – normal is about 2/3 the concentration of blood glucose. Glucose levels may decrease when cells that are not normally present use up (metabolise) the glucose. These may include bacteria or cells present due to inflammation (WBCs) or shed by tumours.

CSF protein – only a small amount is normally present in CSF because proteins are large molecules and do not cross the blood/brain barrier easily. Decreases in CSF protein are not generally considered significant. Increases in protein are most commonly seen with:

CSF lactic acid — often used to distinguish between viral and bacterial meningitis. The level will usually be increased with bacterial and fungal meningitis while it will remain normal or only slightly elevated with viral meningitis.

CSF lactate dehydrogenase (LD) — used to differentiate between bacterial and viral meningitis; may also be elevated with leukaemia or stroke.

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This article was last reviewed on 18 May 2012. | This article was last modified on 21 May 2012.

The review date indicates when the article was last reviewed from beginning to end to ensure that it reflects the most current science. A review may not require any modifications to the article, so the two dates may not always agree.

The modified date indicates that one or more changes were made to the article. Such changes may or may not result from a full review of the article, so the two dates may not always agree.